In electromagnetic valve devices or magnetic valves 1 of the type from the prior art, such as are shown in FIG. 1, an electromagnetic coil 6 is provided which interacts with an armature body 2 and which is accommodated in a coil housing 4. Here, the armature body 2 is guided in a static, hollow cylindrical armature guide tube 8 and can abut against a head part 10, which closes off the armature guide tube 8 at the head side, of the armature guide tube 8 which extends through a central passage opening 12 of the coil housing 4 and through a central opening 14 in a yoke disk 16 at the base side in relation to the coil 6 and which at least partially engages under the yoke disk 16 by means of a radially outwardly projecting annular base part 18.
The armature guide tube 8 is usually of very thin-walled form and has a wall thickness of approximately 0.2 to 0.3 mm. Here, the armature body 2 is preloaded against the head part 10 of the armature guide tube 8 by spring means and is moved in the direction of the core 22, which is held in the armature guide tube 8, by energization of the coil 6, for example in order to actuate a sealing element 25 which interacts with a valve seat 24. When the coil 6 is deenergized, the armature body 2 then bounces in a percussive manner against the head part 10 of the armature guide tube 8 owing to the spring forces. As a result, in particular the head part 10 and also the base part 18 are subject to extreme loading in each case at the edge-like transition to the cylindrical part 19 of the armature guide tube 8. This is because pulsed tensile forces are then exerted on the base part 18 which is supported axially from below against the yoke disk 16, whereas high dynamic compressive forces are exerted on the head part 10, as is easily conceivable from FIG. 1.
Consequently, in practice, the thin-walled armature guide tube 8 cracks in particular in the region of the head part 10 and of the base part 18 owing to the high dynamic axial forces during the impacting. A crack in the armature guide tube 8 then leads to undesired leakage in a pressure medium flow conducted in the magnetic valve 1, which is critical in particular in the case of safety-relevant magnetic valves such as are used for example in pressure-medium-actuated vehicle brake systems.
It has been found in practice that, owing to the typical damage symptoms described above, the armature guide tube 8 is the component most often responsible for a reduction in the service life of the magnetic valve 1.